New Siemens Dishwasher iQ700 - curious about what a noise is

[RinseAndRepeat]

I bought a Siemens iQ 700 dishwasher recently, free standing model, and it's a very nice machine. No complaints at all. Washing flawlessly and the 'Zeolith Drying' works far better than I was expecting it to.

The blue lights are a bit sci-fi but, they're an interesting aesthetic.

I just have one technical question that someone who's perhaps a bit more familiar with these more recent BSH machines might be able to answer:

If you open the dishwasher after it's started, like say even 5 or 6 mins into the wash there's a sound which is like a fan or a vague hiss that keeps running while the door's open. It's not very loud, just like a vague sound of something blowing air. It's definitely not a fault, but I was just wondering what component / system would be making that sound?

 

[appnut]

My boss 800 does the same thing and I don't know why but I really just figured it was part of normal operation so if anyone can enlighten us with what that noise is and what it's for we'd appreciate it

 

[RinseAndRepeat]

I was wondering if it's something to do with the zeolite system or something.

 

[phillymatt53]

Perhaps reading the Owner's Manual might give you a clue.

 

[henene4]

That's the Zeolite system fan.

The fan runs during drying, pulling moist, warm air in. The Zeolite basically forces the water to condense into it, releasing heat, and the air flows back into the tub as hot dry air.


Now, the mineral is damp, so it itself needs to be dried at some point, somehow.
If you'd just do it at any point, you'd get dry mineral - but you'd kind of waste the heat needed to dry the material, and then you could just as well use a heating element and fan for drying.

So, the mineral is dried during the first time any cycle calls for heat.
Instead of using the main heater, the drying fan is activated together with a heating element in the Zeolite container (that heater is about 1300-1400W in the EU).
That means you draw air from the tub, heat it, blow it through the mineral. The mineral heats up, the water stored in it evaporates and is blown out of the container into the wash tub.
There it meets the cold dishes and wash water, where the steam condenses and raises the wash temp.
That means the energy needed to dry the mineral is used to heat the wash.
That's why the fan is running, and to keep anything from overheating, the fan just keeps running for a bit, even if the cycle is paused.


On many cycles, the first fill is heated - mainly the prerinse for intensive and sensor cycles, or the main wash on other cycles.
Very few cycles don't start heating pretty quickly - for example, the Eco cycles here in the EU only heats after the prerinse stage and it's connected full or partial drain, or for example the delicate cycles don't heat in the prerinse.
Meaning that in more than 80% of cases, heating starts right after load sensing, about 4-5 minutes after the initial fill.

 

[RinseAndRepeat]

Perhaps reading the Owner's Manual might give you a clue.

It didn’t, hence my question. Thanks for your most helpful reply…

 

[gelaundry4ever]

I bought a Siemens iQ 700 dishwasher recently, free standing model, and it's a very nice machine. No complaints at all. Washing flawlessly and the 'Zeolith Drying' works far better than I was expecting it to.

The blue lights are a bit sci-fi but, they're an interesting aesthetic.

I just have one technical question that someone who's perhaps a bit more familiar with these more recent BSH machines might be able to answer:

If you open the dishwasher after it's started, like say even 5 or 6 mins into the wash there's a sound which is like a fan or a vague hiss that keeps running while the door's open. It's not very loud, just like a vague sound of something blowing air. It's definitely not a fault, but I was just wondering what component / system would be making that sound?

How do you like it?

 

[gelaundry4ever]

My boss 800 does the same thing and I don't know why but I really just figured it was part of normal operation so if anyone can enlighten us with what that noise is and what it's for we'd appreciate it

It could be the drying fan.

 

[henene4]

I can actually divulge some more information as to why that fan and airflow is quite noisy compared to other noises of the DW.

While the mineral is formed into small pebbles, getting enough air through it with enough heat energy to quickly dry it, you not only need a decent bit of air flow volume, but since the mineral is quite an obstruction, you also need some static pressure.


That's why it's actually kind of the noisiest thing to the point several reviews mention it as annoying and some people went as far as returning the machine.
The quieter the machine is rated the noiser the fan seems as it's not "loud" - it's just a very particular frequency that can be pretty well heard.

 

[gelaundry4ever]

I can actually divulge some more information as to why that fan and airflow is quite noisy compared to other noises of the DW.

While the mineral is formed into small pebbles, getting enough air through it with enough heat energy to quickly dry it, you not only need a decent bit of air flow volume, but since the mineral is quite an obstruction, you also need some static pressure.


That's why it's actually kind of the noisiest thing to the point several reviews mention it as annoying and some people went as far as returning the machine.
The quieter the machine is rated the noiser the fan seems as it's not "loud" - it's just a very particular frequency that can be pretty well heard.

Isn't this true for crystal dry?

 

[henene4]

Yeah
CrystalDry is the marketing term for the US, Zeolith for the EU, with Zeolite being another name for the same mineral AFAIK.

 

[RinseAndRepeat]

I can actually divulge some more information as to why that fan and airflow is quite noisy compared to other noises of the DW.

While the mineral is formed into small pebbles, getting enough air through it with enough heat energy to quickly dry it, you not only need a decent bit of air flow volume, but since the mineral is quite an obstruction, you also need some static pressure.


That's why it's actually kind of the noisiest thing to the point several reviews mention it as annoying and some people went as far as returning the machine.
The quieter the machine is rated the noiser the fan seems as it's not "loud" - it's just a very particular frequency that can be pretty well heard.

This Siemens machine is definitely not noisy - very quiet machine overall. The sound I'm talking about is a very very gentle soft hiss when you only hear if the door is opened during the cycle.

 

[RinseAndRepeat]

How do you like it?

Loads of options - quiet, producing excellent results, very effective drying.

 

[henene4]

This Siemens machine is definitely not noisy - very quiet machine overall. The sound I'm talking about is a very very gentle soft hiss when you only hear if the door is opened during the cycle.

I agree - some don't.
The hiss is the air flow. You should hear a kind of hum when the machine is closed.
That hum is what some people don't like, especially since the machine itself is that quiet